Darth Crandor was a male Sith who served Rovaniss's Sith Empire during the Hidden War. As a young man Crandor was a wealthy smuggler until a near fatal crash caused by a rival lost him his fortune. Crandor fed on his hatred as he healed, discovering the Force within himself. When Rovaniss stumbled across Crandor he instantly saw potential in the man and took him on to join his Sith Empire.
-- Note --
Credit for the helmet idea goes to Jon Treasure's "How To Make A Juggernaut"